It is often required to provide an oral drench to livestock to control internal parasites and other maladies. Sheep are usually drenched twice per year, and goats about four times per year.
It is necessary that the drench chemical should be administered in a volume which varies according to the weight of the animal, and in most instances is approximately proportional to that weight. Because the hand-operated drenchers which are presently used require to be preset for any one volume, it becomes necessary to muster and separate the flock into size groups (sheep, lambs, etc.) before drenching.
In some instances however an operator will rely upon his judgement and not separate the flock, but give a reduced amount from the drenching gun to a smaller animal by not fully operating a control lever on the handpiece (sometimes called a "gun"). This often results in an inappropriate dose, and either an ineffective drench or, if excessive drench chemical is applied, the possibility of damaging or even killing the animal.
In flocks of angora goats for example, the size variation is very evident for various age groups, and there is a large variation in weight between young kids and adult goats.
Hand-operated drench guns as presently used cause hand fatigue, as a strong return spring is required in order to pump the thick solution of drench chemical into the gun before the gun trigger is operated, and this spring pressure must be overcome by hand.
The main object of this invention is to provide means whereby a flock of mixed animals can be appropriately drenched without first separating the animals into weight/size groups, and to be able to administer the correct amount of drench chemical per animal. This will not only be effective in controlling parasites, but also avoid overdrench and possible damage to the animal.
It is a second object of the invention to provide improvements whereby operator fatigue can be reduced, and to provide a means whereby little effort only is required to operate a pump mechanism of a drenching gun or other handpiece.
It is a still further object of the invention to provide means whereby an animal's weight and drench dosage is recorded so as to assist in effective livestock management.